This invention relates to lubricating oil compositions. More specifically, it relates to oil compositions having improved anti-wear properties and other beneficial properties.
It is well known that various additives can be added to lubricating oils in order to improve various oil properties and to make a more satisfactory lubricant. Anti-wear agents are intended to decrease wear of the machine parts. Wear inhibitors for incorporation in motor oils and industrial oils are finding greater use as a result of the greater stress placed on moving parts in high performance engines. Numerous additives have been developed for use in such oil compositions to improve the lubricating characteristics thereof and thereby to lessen the wear of the moving parts. Zinc dialkyl dithiophosphate (ZOP) have been long used as anti-wear additives and anti-oxidants in hydraulic oils, motor oils, and aromatic transmission fluids. In spite of the versatility and long use, zinc dialkyl dithiophosphates have several disadvantages. For example, they decompose thermally producing odorous and corrosive by-products and sludges. Other times they decompose hydrolitically when wet producing H.sub.2 S and oil soluble solids. They corrode copper when wet causing leaks and solid formation. They react with acidic antirusts when wet forming oil-insoluble sticky zinc soaps which plug the filters, valves, servomechanisms and the like. The use of primary alcohols in the zinc dialkyl dithiophosphate manufacturer reduces thermal instability at the expense of increased hydrolitic instability. Additives are known which will reduce metal corrosion by ZOP; however, many of these act by forming a coating on the metal surface which may increase plugging or sticking of the moving parts.
It is an object of this invention to provide a lubricating oil composition having improved anti-wear properties.
It is an object of this invention to provide a lubricating oil composition having good thermal and hydrolytic stability.
It is a further object of this invention to provide a lubricating oil composition having resistance to corrosion.
It is still further an object of this invention to provide an additive composition which does not form oil and soluble soaps.